Neck size could help ID childhood obesity

NEW YORK (Reuters Health) - Measuring children's neck circumference could provide a quick, simple way to screen them for weight problems, a new study suggests.

Such screening is recommended by the U.S. Preventive Services Task Force, an influential panel sponsored by the government's Agency for Healthcare Research and Quality, starting at the age of 6. Right now, doctors usually use body mass index, or BMI, to gauge whether a child (or adult) is overweight or obese. But BMI, which is a ratio of weight to height, is not a good indicator of how much body fat a person has.

Because pounds due to excess body fat -- rather than larger bones or greater muscle mass -- are the health concern, researchers have been looking for more precise ways to gauge fat levels. One way is to measure waist circumference, which studies suggest is better than BMI alone in assessing abdominal fat and health risks, such as high blood pressure, diabetes and heart disease, in adults.

Another tactic is to measure neck circumference -- which, although less studied, seems to be a potential marker of obesity and health risks in adults.

The new study, published in the journal Pediatrics, looked at whether measuring neck circumference has any value in screening children for excess pounds and obesity.

Since BMI is not a precise indicator of body fat, adding a neck circumference measurement could improve childhood obesity screening, lead researcher Dr. Olubukola Nafiu, of the University of Michigan in Ann Arbor, told Reuters Health.

And compared with waistline measurements, measuring the neck would also be quicker and more comfortable for children, Nafiu said, since they can keep all their clothes on for the latter.

Neck circumference is also more consistent in comparison to waist size -- which can swell after a big lunch, for instance.

For their study, Nafiu and his colleagues measured weight, height, waist circumference and neck circumference in 1,102 children and teenagers ages 6 to 18 who were undergoing surgery at their center.

They found that neck circumference correlated well with both BMI and waist size in boys and girls, as well as younger children and teenagers.

The researchers also pinpointed "optimal" cutoff points for neck circumference that identified a majority of kids with a high BMI. For example, a 6-year-old boy with a neck circumference of greater than 28.5 centimeters - about 11.2 inches -- was nearly four times more likely to be overweight or obese, based on BMI, as a 6-year-old boy with a smaller neck circumference.

In addition to helping screen for obesity, the researchers note, neck measurements might also be useful for spotting kids at risk of sleep apnea, a disorder in which tissues at the back the throat temporarily collapse during sleep to create repeated stops and starts in breathing. Obesity, particularly excess weight in the upper body, is a risk factor.

Nafiu said that in earlier studies, he and his colleagues found that children with a high BMI were at relatively greater risk of certain post-surgery problems; they tend, for instance, to take longer to wake up from anesthesia because the drugs concentrate in body fat.

In the future, Nafiu said, the researchers want to look at whether measuring neck circumference before surgery can identify children at greater risk of such problems.